APFIM study of beta and gamma microduplex TiAl intermetallic alloy

beta and gamma microduplex TiAl intermetallic alloy prepared by thermomechanical processing was characterized by atom prove field ion microscope (APFIM) in atomic level. TEM-SAD observation revealed B2 ordering in the beta-phase, while its ordering is expected to be not so high from its composition analysis result and the high temperature deformation mechanism of this alloy. The compositions for each phase determined by APFIM are in good agreement with those determined by TEM-EDX other than the Cr distribution in the beta-phase. However, Cr site occupancy was not determined in the gamma-phase due to a failure in analyzing the ladder diagram probably caused by this materials intrinsic evaporation behavior. Small amounts of ions probably due to oxygen were detected in beta, not in gamma, providing a speculation of oxygen scavenging from the gamma-phase. Hydrides were detected in both the gamma- and beta-phase. (C) 1997 Elsevier Science S.A.